Field of the Invention. The present invention relates generally to the field of orthodontic appliances. More specifically, the present invention discloses a distalizing orthodontic appliance to maintain a desired position or occlusion between anterior and posterior teeth, primarily during class II correction.
Statement of the Problem. In orthodontics, a malocclusion refers to the misalignment of teeth, or an incorrect relation between the teeth of the upper and lower dental arches. With proper occlusion and a full complement of teeth, the mesiobuccal cusp of the upper first molar should align with the buccal groove of the lower first molar. The teeth should all fit on a line of occlusion. For the upper arch, the teeth should form a smooth curve through the central fossae of the posterior teeth and the cingulum of the anterior teeth. For the lower arch, the teeth should form a smooth curve through the buccal cusps of the posterior teeth and the incisal edges of the anterior teeth. Variations from these conditions result in three classes of malocclusion, as follows.
Class I malocclusion, or neutrocclusion, occurs when the relationship of the upper and lower first molars is normal, as discussed above, but the remaining teeth have problems in terms of their spacing, crowding, over- or under-eruption, etc.
Class II malocclusion is also known as distocclusion, retrognathism or overjet. The upper first molars do not rest in the buccal groove of the lower first molars, but rather are positioned anteriorly. The mesiobuccal cusp typically rests in between the lower first molars and the second premolars. This often results in an overbite or protrusion of the upper anterior teeth. In other words, the upper teeth are too far forward with respect to the lower teeth in class II malocclusion.
Class III malocclusion is also known as mesiocclusion, prognathism or negative overjet. The upper first molars are placed posteriorly to the mesiobuccal groove of the lower first molars. Therefore, the lower anterior teeth are more prominent than the upper anterior teeth. Class III malocclusion often occurs when the patient has a large mandible or a short maxillary bone.
In treatment of either class II or III malocclusion, many orthodontists seek to reposition the patient's mandible as a preliminary phase of orthodontic treatment before attaching conventional braces. In particular, the patient's mandible should be repositioned forward (or anteriorly) with respect to the maxilla for class II malocclusion. The mandible should be repositioned rearward (or posteriorly) for class III malocclusion.
A wide variety of orthodontic devices have been invented in the past to bias the mandible either anteriorly or posteriorly. However, a problem arises in that the forces exerted by an orthodontic appliance to bias the mandible toward a desired position must be carried in some manner by the patient's dental anatomy to the underlying skeletal structure. These relatively large forces can undesirably move the patient's teeth during this phase of treatment. Molars are relatively large and can withstand greater forces without movement, and therefore provide a convenient anchor point for some orthodontic appliances. In contrast, anterior teeth are smaller and more easily moved.
Nonetheless, a need exists to avoid undesired movement of teeth that can result from the forces involved in repositioning the patient's mandible. In particular, many orthodontic appliances for repositioning the mandible employ elastics, springs or other types of members extending diagonally from anterior teeth in one dental arch to posterior teeth in the other dental arch (e.g., from the upper cuspids to the lower molars). Devices of this type create a specific need to maintain proper spacing between a patient's anterior teeth and molars during the process of mandible repositioning.
One example of prior art in this field is known as the Carriere appliance, as shown in U.S. Pat. Nos. 6,976,839 (Lluch), 7,618,257 (Lluch), 7,238,022 (Lluch) and 7,985,070 (Carriere Lluch). This appliance has two segments, with an anterior segment bonded to an anterior tooth (e.g., a cuspid) and a posterior segment bonded to a molar. The anterior segment has an elongated arm that extends posteriorly to seat in a ball-and-socket arrangement with the posterior segment. Each individual Carriere appliance allows only a fixed spacing between the teeth. This fixed length dictates that the orthodontist must maintain an inventory of appliances of different sizes and intradental lengths.
Solution to the Problem. The present invention addresses these shortcomings of the Carriere appliance and other similar appliances by providing a distalizing appliance having an elongated member removably attached between a posterior post bonded to a molar and an anterior button bonded to an anterior tooth. One end of the elongated member is equipped with an eye looped around the posterior post, and the tip at the other end is removably seated in a recess in the anterior button. This allows the tip to be cut to any desired length to accommodate any required spacing between the anterior and posterior teeth.
This “one size fits all” approach dramatically reduces inventory requirements for the orthodontist and reduces manufacturing costs. The present invention also has the advantage of being easy to fabricate in the patient's mouth, if desired, without the need to take impressions or send to a lab.
In addition, the eye of the elongated member allows the elongated member to freely rotate about the posterior post to facilitate easy installation and removal of the elongated arm in the office.
The anterior segment of the present invention is able to move in all three planes due to the two areas of articulation provided at both ends of the elongated member. While the segment is connected and anterior-posterior movement of the bonded teeth is fixed, both the anterior and posterior bonded teeth may move separately in all three planes. In contrast, the Carriere appliance allows only one point of articulation, at the ball joint.
The present appliance provides great versatility in changing the degree of resistance or increasing anchorage by bonding additional teeth along the elongated member, if desired.